Heat exchangers typically provide separate flow paths for different media, with heat being exchanged between the media through the materials separating the flow paths. For example, in radiators, a plurality of tubes are commonly provided for carrying heated fluid, with air blown over the tubes (and fins attached to the tubes) so that heat from the fluid is dissipated through the tube walls (and attached fins) to the air, thereby cooling the fluid.
It is important that the flow paths in such heat exchangers facilitate such heat exchange by, for example, maximizing the heat dissipation to the tube walls of the fluid flowing therein, while also minimizing pressure drop in the fluid so as to ensure proper flow of the fluid through the heat exchanger and in the system in which the fluid may be used.
Corrugated inserts or turbulators have been used to facilitate such desired operation. In one example having a corrugated insert in a heat exchanger tube of an oil cooler, the insert has uniform waves with openings in the wave flanks. With such inserts, as indicated in German Utility Model DE 296 22 191 or European Patent EP 742 418 B1, an inflow direction favorable for low pressure loss of the oil lies across the wave trend with an unfavorable one lying precisely in the wave trend. Such inserts can therefore be inserted into the heat exchanger tube so that the wave trend has a certain slope relative to the inflow direction to provide an optimal ratio of cooling performance to pressure loss. However, it is necessary that such inserts be punched out with the corresponding slope angle, so that higher material wastage could possibly occur. Since this is not willingly accepted, in terms of achieving the optimal ratio of cooling performance to pressure loss, relatively large bypasses are often left between the edges of the heat exchanger tube and the edges of the insert. However, such bypasses effect the overall flow characteristics of the heat exchanger and they are therefore often not desirable.
In other heat exchangers such as in flat tubes of charge air coolers or condensers, inserts have been arranged in the heat exchanger tubes so that the inflow direction is situated precisely across the wave trend, in which case openings in the wave flanks need not necessarily be present. However, the advantages of heat exchange provided by fluid flow through multiple wavelengths (through flank openings) are also not received.
The present invention is directed toward overcoming one or more of the problems set forth above.